The reading of a pressure gauge connected to a closed tap is $3.5 \times 10^5 \, N/m^2$. When the tap is opened,the reading of the pressure gauge falls to $3.0 \times 10^5 \, N/m^2$. The velocity of water is ........ $m/s$.

Water is pumped steadily out of a flooded basement at a speed of $10 \ m \ s^{-1}$ through a hose (tube) of radius $1 \ cm$, passing through a window $3 \ m$ above the water level. The power of the pump is (Assume $g = 10 \ m \ s^{-2}$, density of water $= 1000 \ kg \ m^{-3}$): (in $\pi \ W$)

The flow speeds of air on the lower and upper surfaces of the wing of an aeroplane are $v$ and $2v$ respectively. The density of air is $\rho$ and the surface area of the wing is $A$. The dynamic lift on the wing is:

Water is flowing steadily through a horizontal tube of non-uniform cross-section. If the pressure of water is $4 \times 10^4 \ N/m^2$ at a point where the cross-section is $0.02 \ m^2$ and the velocity of flow is $2 \ m/s$,what is the pressure at a point where the cross-section reduces to $0.01 \ m^2$?

At a hydroelectric power plant,the water pressure head is at a height of $300\; m$ and the water flow available is $100\; m^{3} s^{-1}.$ If the turbine generator efficiency is $60\%,$ estimate the electric power available from the plant (in $MW$) $\left(g=9.8\; m s^{-2}\right).$

The figure represents vertical sections of four wings moving horizontally in air. In which case is the force upwards?